The present invention relates to a paging receiver, and in particular to a receiving-message displaying for a paging receiver which utilizes the code of the POCSAG system (Post Office Committee Standard Association Group code format).
The term "Paging receiver" means a mobile radio which receives an individual call signal through a paging station. FIG. 1 is a block diagram of a typical paging receiver, which includes: an antenna 1 for receiving a modulation signal of transmission data propagating on air; a RF (radio frequency) receiving stage 2 for demodulating the modulated signal received through antenna 1 and then reshaping the signal to digital data; a control stage 3 in which data from RF receiving stage is processed and controlled, and various control signals such as a power saving signal are produced; a memory 4 which stores therein frame data to 3 bits and address data of 16 bits for seeking its own specified address data from among specified own data of the received data and which is read out by said control stage 3 upon an initializing sequence according to a power ON of the receiver; an alarm 5 for driving an alarm signal when its own address data is sought under the control of said control means 3; a speaker 6 for producing an alarm sound according to the alarm signal through the alarm; and a display 7 for displaying the received message under the control of said control means 3.
FIG. 2 is a schematic diagram showing a preferred format of the POCSAG code utilizing in a paging receiver, wherein a POCSAG code includes a preamble signal and number of batches, a batch includes a word sync and 8 frames, a frame includes an address code word of 32 bits and a message code word of 32 bits, and therein a transmission speed is 512 bps.
The operational steps of a paging receiver utilizing the POCSAG code will be explained in accordance with above-mentioned configuration. Generally, a paging receiver receives a RF (radio frequency) signal transmitted with modulation into FSK-NRZ (frequency shift keying - non return to zero) through the antenna 1, and the RF receiving means 2 demodulates the RF modulation signal and then reshapes the waveform into a digital signal of binary code. In addition, the memory 4, for which a PROM may be used, stores its own specified address of the paging receiver and its own frame data. Therefore, when control means 3 receives a message of POCSAG code as shown in FIG. 2, it receives a messge of its own frame according to the content of said memory 4, in which the operating steps are as follows.
After detecting a preamble signal received prior to a number of batch messages as (2b) in FIG. 2, a bit synchronization of the data receiving clock is made according to the preamble signal detected and the received data is checked therefrom. The control stage 3 reads out the address data stored in memory 4, stores them to a RAM which is an internal memory, and stores also an address code word among its own frame data received as (2d) in FIG. 2 into the internal RAM. Thereafter they are read out and compared respectively at an accumulator ALU (not shown) of the control means. Then, a message code word among its own frame data is stored in an internal buffer memory and, when the received data compared at accumulator ALU is judged as, an alarm tone is produced through the alarm 5 and the speaker 6. At the same time, a corresponding message is displayed on the display 7.
In a case of a paging receiver adopting a POCSAG code, since the POCSAG code is usually transmitted by 5 digits per unit, display 7 has been applied with a LCD (liquid crystal display) device for displaying 10 digits.
Generally, phone number configurations including an ordinary area code or an intra-office number are as follows.
For a number "5036558940", for example:
phone number 655 8940; PA1 area code 503. PA1 internal exchange number 414; PA1 phone number 7450084. PA1 "503-655-8940"; PA1 "745-0084-414".
for a number "7450084414", for example:
However, in a recent paging receiver, a bit "-" is inserted so that an user can easily recognize the message, and therefore a message of 12 digits is transmitted as below.
In the case of POCSAG code as aforementioned, since a transmitting side transmits 5 digits per one message code word as shown by example (3a) in FIG. 3, the message digits capable of receiving at a paging receiver side become a multiple of 5 such as 5, 10, 15, 20, . . . Therefore, when the display 7 is 10 -digit LCD, the display arrangement is simple, while when it is 12-digit LCD, the display arrangement will be difficult in a paging receiver utilizing a POCSAG code. That is to say, in case of displaying the message of 12 digits, since a transmitting side transmits the 15 digits signal including a space character of 3 digits, a receiving side has to display the message at two times as shown by example (3c) in FIG. 3, and there arises a problem that two memories are required.